4. Function ofVeins:
• Return blood to heart for re-oxygenation and recirculation
• Storage of blood
• 60-80% of resting blood volume in the venous system
• Maintain cardiovascular stability through changes in
capacitance
•Through sympathetic mediated smooth muscle tone
Cronenwett, J. L. and K.W. Johnston (2014).””vascular laboratory” Rutherford'sVascular Surgery 8th edition , Chapter 17-18
5. AMBULATORYVENOUS PRESSURE
■ The sum of the hemodynamic factors involved in venous
insufficiency
■ AVP is defined as the venous pressure in a dorsal foot vein
after 10 tiptoe maneuvers in a standing position.
■ Most physicians consider AVP the “gold standard”
measure of venous hemodynamics.
Cronenwett, J. L. and K.W. Johnston (2014).””vascular laboratory” Rutherford'sVascular Surgery 8th edition , Chapter 17-18
8. Limitation
■ Pressure at the pedal vein may not accurately reflect changes in venous
pressure within the leg, particularly in the deep venous system
■ invasive and time-consuming procedure that may be difficult to perform
in many patients,
– active ulcers
– Severe edema or dermal thickening
Cronenwett, J. L. and K.W. Johnston (2014).””vascular laboratory” Rutherford'sVascular Surgery 8th edition , Chapter 17-18
9. PLETHYSMOGRAPHY
■ Plethysmography is a noninvasive method of estimating changes in
volume in an extremity
■ Strain-gauge plethysmography (SGP)
■ Impedance plethysmography (IPG)
■ Photoplethysmography (PPG)
■ Air plethysmography (APG)
Cronenwett, J. L. and K.W. Johnston (2014).””vascular laboratory” Rutherford'sVascular Surgery 8th edition , Chapter 17-18
10. Plethysmography : Strain Gage Method
Strain gage is made of silicone rubber
tubes, which are filled with conductive
liquid (e.g. mercury) whose impedance
changes with volume.
Venous occlusion cuff is inflated to 40 – 50
mmHg. In this way there will be the
arterial inflow into the limb but no venous
outflow.
Cronenwett, J. L. and K.W. Johnston (2014).””vascular laboratory” Rutherford'sVascular Surgery 8th edition , Chapter 17-18
11. Photoplethysmography
PPG uses light absorbance by hemoglobin as a reflection of blood volume in
the venous and capillary networks in the skin to estimate the degree of venous
stasis
Cronenwett, J. L. and K.W. Johnston (2014).””vascular laboratory” Rutherford'sVascular Surgery 8th edition , Chapter 17-18
12. Interpretation
■ In normal individuals,VRT tends be more than 20 seconds and can
extend to as long as 60 seconds.
■ Significant venous reflux results in aVRT of less than 20 seconds, and
reducing
times generally reflect increasing severity of reflux
■ In the presence of abnormal findings, the test can be repeated with a
tourniquet inflated (50 mm Hg) alternately above and below the knee to
identify the source of reflux
Cronenwett, J. L. and K.W. Johnston (2014).””vascular laboratory” Rutherford'sVascular Surgery 8th edition , Chapter 17-18
14. Interpretation
Cronenwett, J. L. and K.W. Johnston (2014).””vascular laboratory” Rutherford'sVascular Surgery 8th edition , Chapter 17-18
15. Impedanceplethysmography
Different tissues in a body have a different resistivity. Blood is one of the best
conductors in a body ( = 1,5 Ωm)
A constant current is applied via skin
electrodes
The change in the impedance is
measured
The accuracy is often poor or unknown
I = 0,5 – 4 mA rms (SNR)
f = 50 – 100 kHz
(Zskin-electrode+shock)
Z
Z
L
Vol 2
0
2
Cronenwett, J. L. and K.W. Johnston (2014).””vascular laboratory” Rutherford'sVascular Surgery 8th edition , Chapter 17-18
16. ■ Duplex examination : to identify the sites of reflux, evaluate the
deep and perforator systems, and guide intervention.
■ APG serve improvement and predict long-term outcome after intervention
■ PPG is relatively rapid to perform and a reasonable choice to detect venous
disease without details concerning anatomy or the severity of CVI
■ Physiologic assessment with PPG or APG can provide evidence of global
venous dysfunction
SELECTIVE USE OFVENOUS
PHYSIOLOGICTESTING
Cronenwett, J. L. and K.W. Johnston (2014).””vascular laboratory” Rutherford'sVascular Surgery 8th edition , Chapter 17-18
18. Duplex Ultrasound
• Several important roles in phlebology
• Assist in the evaluation of
Deep venous disease
Superficial venous disease
Mapping prior to intervention
Peri‐procedural imaging
Post‐procedural imaging (success, complications,
failure)
Cronenwett, J. L. and K.W. Johnston (2014).””vascular laboratory” Rutherford'sVascular Surgery 8th edition , Chapter 17-18
19. Duplex Ultrasound
•Combination of two imaging modalities
•Doppler
•B mode imaging
Cronenwett, J. L. and K.W. Johnston (2014).””vascular laboratory” Rutherford'sVascular Surgery 8th edition , Chapter 17-18
20. ■ Ultrasound Imaging
Pulses of sound waves are
transmitted into the body
and the returning “echoes”
from various structures are
detected
by the probe and
converted into
images on a screen
Duplex
Ultrasound
Cronenwett, J. L. and K.W. Johnston (2014).””vascular laboratory” Rutherford'sVascular Surgery 8th edition , Chapter 17-18
21. Ultrasound Interpretation ‐ DVT
■ DUS is the test of choice for diagnosis of proximal DVT
• Sensitivity >95%, Specificity >95%
■ Diagnostic components :Visualization, compressibility, flow, and augmentation
•Transducer compression maneuvers
• Doppler evaluation (color and spectral Doppler waveform analysis)
• Augmentation maneuvers
■ Acute DVT
• Loss of compression
• Dilated vein (diameter > artery)
• Intraluminal echoes from thrombus
• Abnormal/absent color Doppler
• Abnormal/absent PW spectral
Cronenwett, J. L. and K.W. Johnston (2014).””vascular laboratory” Rutherford'sVascular Surgery 8th edition , Chapter 17-18
22. Posture
The patient is placed in
a reverseTrendelenburg position
with the knee bent and in
external rotation.
The examination begins below the
inguinal ligament at the common
femoral vein (CFV) and the
saphenofemoral junction (SFJ).
The transducer is placed in
a transverse orientation to the vein
Cronenwett, J. L. and K.W. Johnston (2014).””vascular laboratory” Rutherford'sVascular Surgery 8th edition , Chapter 17-18
23. 1. N Engl J Med. 1989;320(6):342. 2. Bruit. 1982;7:41–42.
24. Ultrasound
Interpretation ‐ DVT
■ • Acuity of thrombus
• Acute (<2 weeks)
• Subacute (2 weeks – 6 months)
• Chronic (>6 months)
• Ultrasound parameters
• B‐mode appearance (hypoechoic,
isoechoic, hyeprechoic)
•Vein lumen size
•Vein wall appearance
•Venous compressibility
• Function of venous valves
• Presence of collaterals
Cronenwett, J. L. and K.W. Johnston (2014).””vascular laboratory” Rutherford'sVascular Surgery 8th edition , Chapter 17-18
25. RecurrentThrombosis
■ Recurrent thrombosis is defined as a repeated thrombotic
event. It may occur in the contralateral or ipsilateral limb
■ Three DUS criteria can be used to diagnose recurrent DVT:
■ extension of the thrombus more than 9 cm,
■ noncompressibility of a vein segment that had previously been
compressible or had previously recanalized,
■ increase in thrombus thickness by 4 mm.
Cronenwett, J. L. and K.W. Johnston (2014).””vascular laboratory” Rutherford'sVascular Surgery 8th edition , Chapter 17-18
27. CentralVein
Stenosis
■ The best sonographic
criterion for detecting
significant vein stenosis
was found to be aV2/V1
ratio of
greater than 2.5 (with
only two false-positive
and false negative test
results reported)
Cronenwett, J. L. and K.W. Johnston (2014).””vascular laboratory” Rutherford'sVascular Surgery 8th edition , Chapter 17-18
28. SuperficialVeinThrombosis
Contiguous extension
of the thrombotic process from the
superficial to the deep veins can occur
in three ways,
- most commonly from the great
saphenous vein (GSV) to the femoral
vein.
- Less often, the thrombus extends
from the small saphenous vein (SSV)
to the popliteal vein.
- Extension through perforator veins to
deep veins can also occur.
Cronenwett, J. L. and K.W. Johnston (2014).””vascular laboratory” Rutherford'sVascular Surgery 8th edition , Chapter 17-18
30. ■ Venous reflux: reversal of flow in the veins of the lower extremity
•Physiologic: fraction of a second it takes for valve leaflets to appose, time varies by
location
•Pathologic: reflux of ≥0.5 seconds in superficial veins
■ Reflux can be elicited by
•Valsalva maneuver
•Augmentation: compression and release distal to point of examination
■ Best results obtained with patient
•Standing with weight on contralateral limb
•Sitting with torso elevated >45 degrees
•ReverseTrendelenberg
Ultrasound –Venous Incompetency
Cronenwett, J. L. and K.W. Johnston (2014).””vascular laboratory” Rutherford'sVascular Surgery 8th edition , Chapter 17-18
31. Examination Protocol
■ Deep system:
•CFV, FV, Popliteal vein
•Reflux >1.0 sec
■ Superficial System: (vein diameter msmtsincluded)
•Entire length of GSV +/‐entire length of SSV
•Reflux >0.5 sec
■ Perforators
– •Examine entire calf
– •Focus on areas of ulcerations
– •Reflux ≥0.35 sec
– •Diameter >3.5 mm likely competent
Ultrasound –Venous Incompetency
Cronenwett, J. L. and K.W. Johnston (2014).””vascular laboratory” Rutherford'sVascular Surgery 8th edition , Chapter 17-18
32. VALVES AND REFLUX
■ There are essentially four ways to check for reflux:
■ 1. Direct visualization of valve closure
■ 2. Doppler waveform evaluation
■ 3. Color flow evaluation
■ 4. Gray-scale evaluation
Cronenwett, J. L. and K.W. Johnston (2014).””vascular laboratory” Rutherford'sVascular Surgery 8th edition , Chapter 17-18
33. Direct visualization of valve closure
Cronenwett, J. L. and K.W. Johnston (2014).””vascular laboratory” Rutherford'sVascular Surgery 8th edition , Chapter 17-18
35. Cronenwett, J. L. and K.W. Johnston (2014).””vascular laboratory” Rutherford'sVascular Surgery 8th edition , Chapter 17-18
36. Cronenwett, J. L. and K.W. Johnston (2014).””vascular laboratory” Rutherford'sVascular Surgery 8th edition , Chapter 17-18
37. Cronenwett, J. L. and K.W. Johnston (2014).””vascular laboratory” Rutherford'sVascular Surgery 8th edition , Chapter 17-18
38. SUMMARY OF GUIDELINES FOR
MANAGEMENT OF PATIENTS WITHVARICOSE
VEINS AND
ASSOCIATED CHRONICVENOUS DISEASE■ Duplex :
39. SUMMARY OF GUIDELINES FOR
MANAGEMENT OF PATIENTS WITHVARICOSE
VEINS AND
ASSOCIATED CHRONICVENOUS DISEASE■ Duplex :
40. SUMMARY OF GUIDELINES FOR
MANAGEMENT OF PATIENTS WITH
VARICOSEVEINS AND
ASSOCIATED CHRONICVENOUS DISEASE
Notas del editor
By placing a small needle into one of the veins on the back of the foot and connecting the needle to a blood pressure measurement machine.
The test has three parts Standing venous pressure is around 90 mmHg
During exercise this should fall to around 30 mmHg.
Note the rapid fall in pressure during 10 calf contractions, indicative of good venous outflow and calf muscle pump function. Also note the slow rise to baseline pressure on completion of thecalf contractions, indicative of absence of venous reflux.
B, Tracing of AVP in a patient with chronic venous insuffciency. Note the higher baseline pressure, slow fall in pressure with tiptoe maneuvers, and high pressure on completion of the contractions, indicative of venousoutflow obstruction and poor calf muscle pump function. Also notethe rapid rise to baseline on completion of the calf contractions, indicative of severe venous reflux.
SGP is designed to detect changes in calf volume after inflation and then rapid deflation of a thigh occlusion cuff SGP provides an estimate of VO obstruction and has primarily been used in the past for the diagnosis of deep venous thrombosis(DVT).
A, Standard position for photoplethysmography (PPG), with the phototransducer located above the medial malleolus.
The transducer is applied to the leg and a baseline recording is obtained.
The patient is then asked to perform five consecutive ankle flexion and extension maneuvers.
The tracing drops as the calf muscles empty the veins. The time taken to recover to 90% of theoriginal baseline tracing after the exertion is completed is recorded as the venous refill time (VRT)
Superfcial venous reflux can be differentiated from deep venous reflux by application of tourniquets to compress the great and small saphenous veins.A tourniquet (latex tubing or blood pressure cuff inflated to 45 mm Hg) is initially placed above theknee. The test is repeated as described previously. If the venous refll time normalizes to longer than20 seconds, the superfcial venous system is implicated as the source of incompetence. If the refll time improves but does not normalize, the dataimply that both the deep and superfcial systems are incompetent
measures changes in size in a large sample area of the lower part of the leg by using an air-filled cuff snuggly applied to the extremity
A low-pressure, air-filled cuff measuring 30 to 40 cm in length is applied to the lower part of the leg from the knee to the ankle.
The air-filled cuff is connected to a plethysmograph and serves as the sensor for changes in volume
A VFI of less than 2 mL/s is associated with clinically normal limbs.
The VFI may be increased to 30 mL/s in severe reflux,
and increasing VFI values indicate moresevere reflux, more symptoms, and higher grades of CVI
Impedance plethysmography measures the change in venous capacitance and rate of emptying of the venous volume on temporary occlusion and release of the occlusion of the venous system.
A cuff is inflated around the upper thigh until the electrical signal has plateaued.
When the cuff is deflated, there is usually rapid outflow and reduction of volume.
With a venous thrombosis, one notes a prolongation of the outflow wave. It is not useful clinically for the detection of calf venous thrombosis and of patients with prior venous thrombosis.
APG better measure of the global venous function of the limb than PPG
that APG accurately separated normal limbs from those with CVI, and with parameters that significantly differentiated the two groups wereVFI, VV, EF, and RVF
the best screening, perioperative, and follow-up tool available for the evaluation ofvascular disease. In the assessment of venous disease, DUS is used to detect acute deep venous thrombosis (DVT) and venous reflux and to evaluate chronic venous obstruction
An angle of insonation of 45to 60 degrees between the transducer and the vein should beused to achieve the optimum Doppler waveform.
The four components that should be examined : Visualization, compressibility, flow, and augmentation
Recurrent thrombosis in the common femoral vein in a patient with limb swelling and chest pain. The patient previously had afemoropopliteal thrombosis documented in our hospital. The vein contains both echogenic (downward arrow) and echolucent (upward arrow)material (left panel). It is dilated (significantly larger than the common femoral artery, arrow, right panel) and noncompressible.
Direct visualization of valve closur
Using color Doppler, the examiner views the blood flow in the vein moving away from the transducer (back toward the heart), displayed as blue
(A). During the Valsalva maneuver, the direction of blood flow reverses to red, suggesting the presence of venous reflux
(B). If the valves were competent, no flow would be seen during the Valsalva maneuver.
Color flow images demonstrating valvular incompetence.
A, Venous flow is antegrade through an incompetent valve when manual compression is applied distal to the valve.
B, Blood flow direction is retrograde (reflux) through the incompetent valve when manual compression is released.
(Color assignment is red for flow toward the transducer and
blue for flow away from the transducer.)
Reflux displayed using Doppler spectral analysis. Note how flow is below the base line at rest and switches to above the line with Valsalva. If the valves were competent, no flow would be seen during the Valsalva maneuver.